This invention relates to a circular knitting machine provided with pattern creating devices.
In general, a circular knitting machine comprises a cylinder rotatable in one direction and provided in its peripheral surface with a series of circumferentially spaced needle slots, a series of individually movable knitting needles reciprocated in the associated needle slots, a series of jacks arranged below the associated needles in end to end relationship for reciprocating with the associated needles in the needle slots, each of the jacks having a butt extending out of the associated needle slot, and a camming mechanism including a number of raising cams arranged to define a cam track through which each butt passes when the cylinder is rotating. The knitting can be effected whenever each butt of the jack comes in contact with the raising cams and is thereby moved along with the associated needle upwardly in the associated needle slot.
In such a prior art circular knitting machine, e.g., a circular knitting machine as disclosed in Japanese Pat. Publication No. 46-7232 (No. 7232/71), in order to produce patterns, each of the jacks is formed with a resilient hanging down extension having a bottom butt extending from the bottom of the extension and urged by the resilience of the resilient extension to a position in which it is engageable with the raising cams. A presser is provided for each jack and it is mounted for pivotal motion. The upper and lower end portions of each presser are adapted to be normally inclined inwardly and outwardly of the cylinder by the resilience of the hanging down extension. An electrical magnet is provided for each presser, which corresponds in position to the upper end of each of the pressers so that, when energized, it can selectively attract the upper end of the presser to hold the presser, against the resilience of the hanging down extension, in a condition such that the upper and lower end portions of each presser are inclined outwardly and inwardly of the cylinder. When the presser is in such a condition, the bottom butt of the particular jack extension is temporarily retracted from the aforesaid position in which it is engageable with the raising cams, whereby the associated latch needle is prevented from making the upward movement and effecting the knitting operation, thus producing patterned fabrics.
However, the above prior art circular knitting machine has to have the latch needle, the jack and the presser in each associated needle slot of a relatively narrow width so as to interact to perform the desired operations. This makes it very difficult to assemble these elements into the cylinder in manufacturing the circular knitting machine because of a much greater number of elements. In addition, the prior art circular knitting machine requires that the bottom butt of the jack be arranged to move in a cam track while the electrical magnet is arranged to correspond in position to the upper end portion of the presser, which is not an integral portion of the jack, so that an appropriate adjustment of the relative positions therebetween is very hard to accomplish unless the elements are precisely machined and assembled into the circular knitting machine with special attention. Thus, the prior art circular knitting machine is very hard to manufacture.